According to estimations from the mid-80s, the future soviet tank (FST-3) had enough armor to defeat anti-tank ammunition fired from a current 120mm powder gun. Future NATO tank guns would have to produce 18MJ worth of energy at the muzzle, for the penetrator of an armor piercing fin-stabilized discarding sabot (APFSDS) – double the energy produced by the Rheinmetall 120mm L/44 gun mounted on the Leopard 2 and M1A1 Abrams (produced in the United States as the M256).¹ A number of solutions were proposed, including the use of a 140mm solid propellant gun. There were a number of more extravagant solutions, including electromagnetic acceleration and electrothermal-chemical ignition and control. Despite the wide array of options in regards to enhancing vehicle lethality, the easiest and fastest solution remains the adoption of a 140mm powder (solid propellant) tank gun. In fact, most tank-producing nations have developed a number of 140mm cannons for use in future tanks and 140mm guns have been fitted into existing turrets; however, no nation has seriously considered the use of a 140mm gun. Since the late 70s tank enthusiasts have been predicting the introduction of larger caliber weapons. Yet, no Israeli Merkava tank has been seen with a 140mm tank gun² and no Russian tank has been seriously developed with a 152mm piece.³ On the other hand, development continues with electrothermal-chemical technology for use in tank guns, and some still see electromagnetic propulsion as the future in tank armament.

Nevertheless, calibers larger than 120mm are still enticing and see extensive use in NationStates. Especially popular are either the 152mm or 155mm calibers. The use of both these calibers has been popular ever since the publication of multiple articles giving estimations on the armament of the Black Eagle – a T-80U turret upgrade – and the future T-95.⁴ It should be noted that the Black Eagle turret mounts a solid propellant 125mm tank gun, probably the 2A46M-4 tank gun adopted on the T-80UE.⁵ The T-95s armament, admittedly, remains a mystery, along with the rest of the tank. There have been actual attempts to mount a larger caliber tank gun into existing tank turrets, although very few details are published about these projects. The Swiss mounted a NATO 140mm gun into a Panzer 87⁶ and the Russians have recently introduced a long 152mm cannon into a T-80, with some turret extensions in the front and a bustle in the rear. It’s possible that there have been prototypes of a 140mm armed main battle tank in the United States of America, although the main battle tank program was canceled in 1995.⁷



The lack of information on the development and testing of tank guns of a caliber between 130mm and 160mm admittedly makes it difficult to understand the consequences of implementing a gun of this caliber. These negative side effects of increasing lethality through increasing caliber only accumulate as the caliber gets larger – i.e. the effects of using a 155mm gun are much greater than those of using a 140mm gun. Consequently, oftentimes the use of these heavy cannons in tank designs in NationStates doesn’t accurately portray the negative side effects. Although this isn’t necessarily the author’s fault, it’s a mistake that should be corrected. This informative is an attempt to explain the advantages, as well as the various disadvantages, of larger caliber tank armaments. These disadvantages include increased turret volume, potential increase in hull volume and increase in weight. The informative’s argument is that these increases in volume and weight do not justify the increased lethality, especially given that there are many alternative options in tank gun technology.

140mm+ caliber lethality
The original goal, as stated above, was to achieve muzzle energy of 18MJ. In tank armor penetration by kinetic energy (armor piercing fin stabilized discarding sabot – APFSDS) the principle (and the simplest) factors which effect penetration are velocity and mass.⁸ Therefore, the simplest equation which can given an idea of a round’s penetration is KE = ½m •v². With an increase in muzzle energy you can either increase mass or velocity of the round. With a decrease in mass there is an increase in velocity, and the same is true vice versa. This greater muzzle energy is established through the use of larger propellant charges – larger barrels can withstand larger charges because the created pressure during gas expansion is distributed along a greater surface area. The idea is the same in high-pressure guns, except that special materials are used to withstand higher pressure in the breech and barrel.⁹ Although the common goal is 18MJ, there is nothing that suggests that the muzzle energy produced by a 140mm caliber tank gun is and always will be 18MJ. The performance of a 140mm gun, and any gun, is based only upon the construction quality of the barrel, breech and round and the quality and volume of the propellant. In fact, a 140mm gun may produce only 16 or 17MJ of energy.¹⁰

According to Rheinmetall, a 140mm tank gun produces energy of 23MJ at the muzzle. However, only 14MJ are relevant to the penetrator itself.¹¹ Fired from a NATO 140mm gun, a tungsten heavy alloy (WHA) penetrator with a length to diameter (L:d) ratio of will penetrate roughly 830mm of rolled homogenous steel after penetrating a 400mm ceramic module (the ceramic is not necessarily encased in steel).¹² Due to the considerable power achieved by the 140mm powder gun and the availability of the technology, it was thought as early as 1989 that the 140mm would be used as a stop-gap solution.¹³ The amount of technology demonstrators of this caliber make it apparent that at one point in time it was a real solution. The U.S. XM291 solid propellant gun showcased a breech which could fit both a long 120mm cannon and a 140mm cannon if it was necessary in the future.¹⁴ However, today the 140mm gun is no longer considered a real option by any NATO tank-producing country.¹⁵ Instead, the Germans introduced the new 55-caliber long 120mm tube and the DM53 APFSDS in the KWS I upgrade of the Leopard 2A5 (the 2A4 to 2A5 upgrade is the KWS II, which increases the depth of the front armor array).¹⁶ The XM291 120mm tube is also longer than the current M256 (a copy of the Rheinmetall 120mm L/44), but was never implemented and there is still no gun modernization program in sight.^17,18



Although the 140mm tank gun, and any caliber above 120mm, offers better ballistics than existing 120mm solid propellant guns against current and future armored threats, the large-caliber gun was a solution based on the lack of time.¹⁹ Prior to the fall of the Soviet Union the FST-2 and FST-3 were considered threats beyond the capabilities of NATO tanks of that time, including the M1A1 and Leopard 2. The M1A1HA (heavy armor) upgrade was introduced at a cost of around $1 billion due to the threat posed by the theoretical FST-2.²⁰ Beginning in 1988, there were 1,328 M1A1HA tanks manufactured and another 834 with increased armor protection (M1A!HA+).²¹ However, the Soviet Union fell in 1991 without producing either the FST-2 or the FST-3. Thankfully, the fall of the Soviet Union has allowed us to take a closer look at the advantages of a 140mm gun. The pace of development has decreased, along with decreased budgets for research and design work on advanced tank armaments. Instead, work has been put into upgrading the lethality of light armored fighting vehicles for deployment in peace keeping operations. This has given Western nations a chance to develop next-generation armaments in the 120mm caliber. However, if NATO wants to design a future tank with MLC 60 or 50 as its weight limit, tank designers will have to look for a smaller caliber solution.

Disadvantages
Even with a decrease in the ammunition held, the volume of thirty 140mm rounds would be roughly 3.05m³. An individual 140mm APFSDS could weigh as high as 40kg, while a 120mm APFSDS weighs between 19 and 23k. This means that thirty 140mm rounds would weigh roughly 1,200kg as compared to the 830kg of a forty round 120mm ammunition load. ²² Rheinmetall’s 120mm L/44 weighs 1,190kg, while the L/55 version increases the weight to 1,347kg. GIAT’s (now Nexter) 120mm F1 weighs 2,800kg and the M256 weighs 1,901kg. The high-pressure MG251 weighs roughly 3,300kg.²³ However, let’s take Rheinmetall’s L/55 and the XM291 as the more recent in solid propellant technology (the XM291 saves about 600kg worth of weigh as compared to the M256). In comparison, a 140mm gun (including the trunnions) would weigh over 3,200kg. It would also require a breaking force of up to 1,200KN.²⁴ In gun weight and ammunition weight alone the increase in weigh would be about 1.5 metric tons. The necessary increase in turret volume to allow a depression of the main gun to anywhere between 7º and 10º could cost another 5 to 6 metric tones in weight. The increase in gun caliber would also result in an increase in the size of the mantlet, resulting in another increase in armor volume and weight. In fact, a total weight increase due to the larger turret armor volume could amount to up to over 10 metric tons.²⁵ Insofar, the total weight increase amounts to closer to 15 metric tones. Taking the weight of the Leopard 2E of around 63,000kg²⁶, it would mean that based on what we have figured out a 140mm tank with the same proportions of mobility, protection and lethality would weigh almost 78,000kg. In order to keep within the maximum acceptable ground pressure of 9N/cm² the chassis would also have to be enlarged in both width and length. The increase in weight of a 140mm gun, with a proportional increase in protection and mobility, would be a far greater difference to existing main battle tanks than is the difference between the M60 (52,000kg²⁷) and the M1A2 (roughly 64,000 to 65,000kg²⁸).

The maximum width of the vehicle is dictated by what is allowed by a nation’s rail system. The amounts of distance between any given points in the majority of nations in NationStates make travel by tank track improbable. NATO armies, and their allies, have always used track, while the Soviets have always had the philosophy that a tank should be prepared to travel great distances on its own tracks. But, the Soviets have traded other aspects of their tanks for increased engine life. In terms of track life, the AMX-30’s tracks could travel an average of 5,000km. ²⁹ Track life of current tracks is most likely similar, as no major innovations with track durability have really been made. Fuel considerations make travel by truck over long distances as improbable as travel by one’s own track. Currently, Spain’s truck transport can fit a single Leopard 2E or two Pizarro infantry combat vehicles. Assuming that a truck was made to carry a much larger main battle tank it would still only be able to carry one. Taking into consideration tank fleets in NationStates, let alone distance to travel, the amount of trucks required to transport armor material across the country would exceed a country’s capability. The width of a nation’s highway lane also plays apart in the allowable width of a tank. The use of multi-lane highways solves the problem to a certain degree, but doesn’t get rid of it. The costs of constructing a multi-lane highway network across a country the size of the Soviet Union would not allow a nation to procure an expensive main battle tank! On a more serious note, it’s not realistic to assume that a nation can change the width of its tracks to accommodate a larger main battle tank. Therefore, there exists a physical limit on the width of any main battle tank.

Battlefield mobility of a tank is dictated by the relationship between the length of the track touching the ground and the width between the centerlines of each track. Ratios of over 1.5 will disallow a tank from making quick turns, and may even cause a crew to damage or break the tank’s transmission. Given the maximum allowable gun pressure we know that there is a maximum allowable weight per width. Width is hard to increase due to road and rail constraints. Consequently, one could say that there is a maximum weight limit of a tank. Taking into consideration Western rail gauge, this limit seems to be MLC 70 (roughly 64,000kg). Therefore, a 78,000kg tank would find it hard to strategically deploy long distances, not to mention the ability to deploy overseas!

Even so, 78,000kg doesn’t take into consideration several more weight augmentations. An increased weight requires increased engine volume and fuel volume. Fuel tanks, within themselves, constitute a substantial increase in weight due to protection requirements. It would be nearly impossible for a human loader to load 40kg ammunition in the ideal loading time of 5 to 7 seconds, and therefore an automatic loader would be necessary. Nevertheless, the weight of the ammunition would require a loading system of at least 600kg, so there are no weight savings in that area. And, we are assuming an armor protection equal to current tanks. Ideally, a 140mm armed tank would also have an increase in armor protection. That constitutes a large increase in weight. 35 metric tons of the Abram’s weight is armor,³⁰ meaning we’re looking at a weight increase of armor by a factor of at least ten metric tons. In terms of aerial density armor protection can weigh up to 4 metric tones per meter.³¹ Therefore, if current lethality and protection patterns are kept the 140mm armed tank could weigh well over 80,000kg.



Taking weight into consideration, one should also figure in logistics. The cost of logistics can be related to as the eighth power of the tank’s weight (for a tank of the weight we’re discussing).³² Therefore, the logistics slice of a 80 ton tank would be roughly 5 times greater than an existing 63 ton tank! And this fails to mention the cost of construction of each individual tank. The cost considerations in manpower, man hours and logistics resources are exponentially greater than those in a modern real-life main battle tank. The use of advanced technologies, such as computerized active hydropneumatic suspensions and computerized transmissions will add to the cost of the tank, but this fact remains the same in all tank design.

Unconventional Solutions
If weight is the principle cause of the problem, any user of a large caliber tank gun should look into solutions which reduce weight. Nominally, this means unconventional turret designs. As an example, Jordan’s King Abdullah Development and Design Bureau (Kaddb) revealed the new Falcon turret at Idex 2001. The turret is designed to reduce he frontal profile as much as possible (although, it should be known that the smaller the frontal profile of the turret, the larger the sides will be³³), as well as weight, and is an upgrade option for Arab M60 Patton tanks and Jordan’s own Challengers (Al Husseins). The two man turret crew (the driver is still in the hull) is seated in the turret basket, reducing the required amount of protection in the front. By reducing the front turret profile and moving the position of the crew Kaddb radically decreased the armored volume of the turret reducing weight just as dramatically. However, moving the crew into the turret basket results in disallowing the tank commander from a good panoramic view – in essence, he’s commanding the tank based on computers. Furthermore, the Falcon turret’s autoloader only holds eleven rounds (with plans to increase to sixteen), compared to the forty rounds held by the M1 Abrams³⁴ – the Falcon turret is wedded to Ruag’s 120mm compact tank gun (CTG), which weighs 2,600kg.³⁵

Reducing turret volume, as shown by the Falcon turret upgrade, is always an option and may result in a hefty reduction of weight, given the reduction in armored value. As a reference, assuming full nuclear, biological and chemical (NBC) protection each crew member will require about .4m³ and the loader .8m³ to achieve the fastest loading rate possible (as close to 5 seconds as possible)³⁶ and to this we add another 10% for crew comfort and freedom of movement. So we can come to the conclusion that a conventional four man crew requires just about 2.5m³ in terms of volume. This is even larger for tanks which attempt to move the driver into the turret, since that driver now needs to counter-rotate meaning his required volume will be based on the spine of his seat and not on his center of mass, effectively doubling the required volume. A three man crew, however, requires less than 2m³ plus the required volume for the tank autolading system. In terms of turret volume, however, we’re talking about a volume reduction of a little bit over 1m³. Jordan pays the price in the weight of its gun (heavier breech) and the relatively small ammunition hold, and the inability to replenish the autoloader’s ammunition under armor (instead, the crew has to replenish from the outside). One can also reduce the crew from four or three to two, reducing fighting compartment volume from 10m³ to around 3m³. ³⁷ There are, as always, important considerations including the requirement to train multiple crews per tank – a two-man crew will not be able to successfully guard the tank at night, or maintain the tank on their own. Furthermore, each crew member now has a larger share of the tasks.³⁸

Other turret options include the cleft turret and the externally mounted gun. The former reduces turret volume, and the latter almost gets rid of it completely (you only have to armor the breech against small arms). Both have huge ballistic weaknesses, although if you can guarantee the first-round and the necessary lethality of that first-round then ballistic weaknesses are almost irrelevant.

However, it’s questionable whether a 140mm solid propellant gun or even a 155mm solid propellant gun can penetrate the armor of a NationStates tank on the first hit. Let’s say that a M289A3 APFSDS scaled up to be fired from a 140mm gun (larger mass) has a penetration of roughly 1,200mm of RHAe (rolled homogenous armor equivalent); this is still insufficient to penetrate a large number of tanks with over 2,000mm RHAe along the front 60º arc. Always hitting the side armor is unlikely, as that’s what the Israelis did during the Six Day War yet close to 35% of the hits are registered to hit the tank front 60º. During the Yom Kippur War near 55% of the hits were registered on the front 60º and during the Second World War (the most ‘copied’ war of NationStates) this percentage increases up to the 70% mark! ³⁹ This doesn’t even begin to take into consideration the armor protection between the 60º and 90º protection arc in main battle tanks, or up to the 120º degree arc! The Black Eagle, for example, has explosive reactive armor integrated into the front 120º arc of the turret.⁴⁰ One source claims a turret armor protection of up to 880mm for the Black Eagle, although if an improvement in side turret front armor over the T-80U is assumed then we’re looking at more than 400mm worth of protection against kinetic energy (KE) threats in terms of conventional armor.⁴¹ If Kontakt-5 provides 300mm worth of equivalent armor against APFSDS,⁴² then it’s possible that the Black Eagle has a side turret front protection level of over 700mm RHAe, and possibly up to 800mm RHAe. That means that the Black Eagle may have a side turret front armor protection level close to the front protection level of current generation main battle tanks. Improvement in passive armor thickness and mass efficiency, as well as improvements in explosive reactive armor, might mean an even higher level of protection. Although the Black Eagle is not going to be adopted by the Russian Army, it serves as an example as what future tanks can achieve (like the T-95).



For example, with a weight increase of just 1.5 to 2.5 metric tons⁴³ the M1A2 SEP can adopt a heavy explosive reactive armor suite increasing protection by about 300mm RHAe. This would increase effective protection along the front 60º arc to over 1,200mm RHAe and the side turret front armor to about 650mm RHAe. ⁴⁴ The most important consideration to take into consideration is that Kontakt-5 explosive reactive armor proved to completely stop the M289 APFSDS.⁴⁵ Although the new M289A3 APFSD was specifically designed to defeat Russian explosive reactive armor, new reactive armor concepts may prove more difficult to puncture. For example, Ukraine’s Nozh explosive reactive armor uses a series of explosively formed penetrators to literally cut the APFSDS into several pieces. However, Nozh suffers from the disadvantage of relying on a dramatic impact angle. Regardless, the point remains that the efficiency of explosive reactive armor shouldn’t be measured in RHAe as opposed to its ability to break the incoming APFSDS.

This takes us back to turret design. If one can reduce armor volume to reduce weight, one can rearrange previous armor in order to increase the thickness of the surface area left. In other words, a tank with a narrow mantlet turret can have an increased thickness in armor for no penalty in weight (you just don’t lose the weight). So, if by maximizing line of sight thickness of the armor, like the Leopard 2A5, a future tank can achieve armor protection of around 1,500mm RHAe then a 140mm gun is incapable of penetrating the frontal arc of that tank. Of course, an electrothermal-chemical gun might be incapable as well, but it doesn’t have the added weight penalties!

Technological solutions
There are advances in tank technology which may allow for weight savings. The German MTU 880 series of diesel engines produce around 215kW/m³, a substantial improvement over prior diesels – it is 35% smaller in volume and 14% lighter in weight.⁴⁶ In other words, the MTU 880 produces 288hp/m³, which means that to provide a hp/t ratio of at least 20:1 the engine bay would require at least 5.6m³ (based on a 80,000kg tank). This would produce 1,600hp, while a 2,000hp engine would require about another 2m³ worth of volume. MTU claims that the MTU 890 series engine is 50% smaller than the MTU 880 series in terms of volume⁴⁷, which to me says that the MTU 890 can produce 430kW/m³, or that a 1,600hp engine bay would require a volume of about 2.8m3. There are claims that the MTU 890 produces 1.2MW/m³, ⁴⁸ but these are highly suspect – nevertheless, the lack of an alternate source disallows me from discarding the figure. Nevertheless, use this latter figure as carefully as possible; else we might have another buckyball trend! Regardless, new diesel engines provide a heavy savings in weight, forgive the pun.

There are also weight savings in the areas of future transmission systems, and the use of certain materials in vehicle and armor construction.⁴⁹ Alternate armor could be a consideration, or even the reduction of armor protection to save mobility. This concept was the guideline for the French AMX-30⁵⁰ and the German Leopard 1,⁵¹ and may have been the guideline for the U.S. future main battle tank (FMBT) which aimed for a combat weight of 20 metric tons.⁵² Of course, the problem isn’t as severe as it is for a twenty ton tank with the goals of a sixty ton tank, but there are similarities. While technological breakthroughs may save some weight, any heavy NS tank design that scales up with current technology will have to rely more on ingenuity than on technology. Cost should also be taken into consideration when using high technology. Currently, more than 60% of a tank’s cost is the high technology and electronics used. ⁵³ If a M1A2 costs $5.4 million to produce⁵⁴ then $3.24 million is applied to electronics. That said, any future tank with the most advanced in terms of electronics and high technology to save weight or enhance features that now have to support greater weight may cost over $10 million. These systems include electric transmission, active hydropneumatic suspension and advanced remote controlled weapon stations. There’s also a high cost in the technology provided to manufacture certain parts of the future tank (like advanced armor).

Alternatives
There are great deals of alternatives to 140mm guns in smaller calibers which can be explored.⁵⁵ This includes the more well known electrothermal-chemical technology, which will provide the necessary energy to match the muzzle energy of a 140mm gun. Unfortunately, this comes with the added costs. Technologies which may be applied to the future, assuming advances in energy storage and efficiencies, are electromagnetic propulsion systems – for example, rail guns and coil guns. However, these are not solutions to be considered for a long while. Simpler alternatives are improved solid propellant guns. The 120mm L/55 firing the DM63 can penetrate as much as 900mm of rolled homogenous steel, ⁵⁶ while the penetration of the same gun firing the M289A3 may exceed 1,000mm of penetration! Advanced solid propellants might also offer short-term improvements in lethality, with smoother burn patterns and higher amounts of energy per volume. The alternatives are out there, they just require some researching!



On the other hand, advances are in the form of the ammunition. Rounds like the XM943 can engage tanks at long ranges and defeat them by engaging the roof armor with an explosively formed penetrator⁵⁷ – in other words, a gun-launched long-range anti-tank missile. Rounds like SADARM⁵⁸ can drop multiple submunitions on a target, increasing chances of penetration. This type of guided ammunition greatly increases the engagement ranges of tanks and questions the requirement of heavy armor. For example, a 155mm howitzer can knock out one or more tanks using submunitions while those tanks can’t even respond. The introduction of indirect fire munitions may merge the roles of heavy armor and self-propelled artillery, although the former could never provide the necessities for occupation (the lack of heavy protection) while the latter is simply too expensive to replace the artillery vehicle. Indirect fire munitions may also argue in support of large guns – the larger the gun, the larger the round the more submunitions it can hold. However, it also argues for the use of smaller caliber guns. A tank designed with a 105mm high velocity gun has superior mobility than larger variants, may have an equal level of protection and can engage enemy tanks at non-line of sight (NLOS) ranges. Its armor protection would be enough to protect it against infantry armaments such as light anti-tank rockets or top-attack missiles through the use of explosive reactive armor and an active protection system. It would also be cheaper and a nation could deploy more for the same costs.

In the end, the use of alternatives is up to the creator. There are always design specifications and operational requirements to take into consideration. Each creator might also have different opinions and perspectives. It’s all part of the game. However, it’s important to always take into consideration the advantages and disadvantages of any given piece of equipment – including large caliber tank guns.






1. Orgorkiewicz, R.M., Future Tank Guns, Part I: solid and liquid propellant guns, Janes International Defense Review, 12/1990, p. 1377
2. Eshel, David, The Merkava Mk. 3 Defies Its Critics, ARMOR Magazine, 1 May 2000, p. 17.
3. Warford, Jim, The Resurrection of Russian Armor: Surprises from Siberia, ARMOR Magazine, 1 September 1998, p. 32.
4. Ibid. pp. 32-33.
5. Baryatinskiy, Mikhail, Main Battle Tank T-80 (Russian Armor), Ian Allen Publishing, 2007, p. 93
6. Panzer 87 refers to the name of Swiss produced Leopard 2A4s.
7. Acquisition of the Advanced Tank Armament System, Department of Defense, 28 February 2001
8. Simpkin, Richard E., Tank Warfare: An analysis of Soviet and NATO tank philosophy, Brassey’s, 1979, p. 90.
9. http://www.rheinmetall-defence.com/index.p...47&lang=3&pdb=1
10. Diamond, P., Electro Thermal Chemical Gun Technology Study, MITRE, March 1999, p. 5.
11. Kruse, Dr. Josef and Weise, Dr. Thomas, Studies on Germany’s Future 140mm Tank Gun Systems – Conventional and ETC -, 34th Gun & Ammunition Symposium & Exhibition, 26 April 1999, p. 12.
12. Horst, Albert W., et. al., Recent advances in anti-armor technology, American Institute of Aeronautics and Astronautics, Inc., January 1997, p. 18.
13. Pengelley, Rupert, A new era in tank man armament: the options multiply, Janes International Defense Review,11/1989, p. 1522.
14. Ibid.
15. Sharoni, Asher H. and Bacon, Lwarence D., The Future Combat System, Part Two: Armament, ARMOR Magazine, September 1997, p. 29.
16. Schnellbacher, U. and Jerchel, M., Leopard 2 Main Battle Tank 1979-1998, Osprey Publishing, pp. 24-36.
17. Hilmes, Rolf, Arming Future MBTs – Some Considerations, Military Technology, December 2004, p. 76.
18. It should be considered that there exists plans to integrate the XM291 or XM36 tank guns into existing armoured vehicles, and the XM36 will be used in the future combat system line-of-sight gun vehicle. This technology may be spiralled down to the M1 Abrams in a M1A3 upgrade. Dyvik, Jahn, et. al., Recent Activities in Electrothermal Chemical Launcher Technologies at BAE Systems, IEEE Transactions on Magnetics, January 2007.
19. Sauerwein, Brigitte, Rheinmetall’s NPzK, Janes International Defense Review, 2/1990
20. Warford, Jim, The Resurrection of Russian Armor: Surprises from Siberia, ARMOR Magazine, 1 September 1998, p. 32.
21. Green, Michael, M1 Abrams at War, Zenith Press, 2005, pp. 25-28.
22. Hilmes, Rolf, Aspects of Future MBT Conception, Military Technology, 30 June 1999.
23. Maxwell, David, New Tanks For Old, Part II: Tank Top Upgrades, Armada International, June 2002, p. 82.
24. Hilmes, Rolf, Aspects of Future MBT Conception, Military Technology, 30 June 1999.
25. Simpkin, Richard E., Tank Warfare: An analysis of Soviet and NATO tank philosophy, Brassey’s, 1979, p. 137.
26. The Osprey book only gives the weight of the Leopard 2A4. The Leopard 2E is, in any case, more or less the same as the Leopard 2A6M and the Swedish Strv. 121 (the Swedish vehicle doesn’t offer the L/55 main gun, however). Candil, Antonio J., Leopard 2 daneses en Córdoba, Fuerzas Terrestres, Vol. 3º, N.º 36, Año III, p. 62.
27. Lathrop, R., and McDonald, J., M60 Main Battle Tank 1960-91, Osprey Publishing, 2003, p. 28.
28. Green, Michael, M1 Abrams at War, Zenith Press, 2005, p. 31.
29. Ogorkiewicz, R.M., AMX-30 Battle Tank, Profile Publications Limited, December 1973, p. 12.
30. Zahn, Brian R., The Future Combat System: Minimizing Risk While Maximizing Capability, USAWC Strategy Research Project, p. 24.
31. Hilmes, Rolf, Aspects of Future MBT Conception, Military Technology, 30 June 1999.
32. Simpkin, Richard E., Tank Warfare: An analysis of Soviet and NATO tank philosophy, Brassey’s, 1979, p. 103.
33. Ibid., p. 141.
34. Huntiller, Mark, New Turret a New Tank Make?, Armada International, March 2004, p. 22. Information on Falcon turret is from this article.
35. Maxwell, David, New Tanks For Old, Part II: Tank Top Upgrades, Armada International, June 2002, p. 82.
36. Simpkin, Richard E., Tank Warfare: An analysis of Soviet and NATO tank philosophy, Brassey’s, 1979, p. 133.
37. Hilmes, Rolf, Aspects of Future MBT Conception, Military Technology, 30 June 1999.
38. Sharoni, Asher H. and Bacon, Lwarence D., The Future Combat System, Part Three: Powering the new system, ARMOR Magazine, January 1998, p. 37.
39. Held, Manfred, Warhead Hit Distribution on Main Battle Tanks in the Gulf War, Journal of Battlefield Technology, March 2000, p. 7.
40. Baryatinskiy, Mikhail, Main Battle Tank T-80 (Russian Armor), Ian Allen Publishing, 2007, p. 93
41. Lakowski, Paul, Armor Technology.
42. Robb McLeod, Modern Explosive Reactive Armours, Russianarmor.info, 1998.
43. http://www.drdo.org/pub/techfocus/feb04/explosive.htm
44. M1A2 armor estimates taken from: Lakowski, Paul, Armor Technology.
45. Warford, Jim, The Resurrection of Russian Armor: Surprises from Siberia, ARMOR Magazine, 1 September 1998, p. 31.
46. Hilmes, Rolf, Aspects of Future MBT Conception, Military Technology, 30 June 1999.
47. http://www.mtu-online.com/en/appl/applmili/applmilicomb/
48. Compact Power Plants, DaimlerChrysler High Tech Report, February 2004.
49. Armor will be discussed in a future Informative.
50. Ogorkiewicz, R.M., AMX-30 Battle Tank, Profile Publications Limited, December 1973, p. 6.
51. Jerchel, Michael, Leopard 1 Main Battle Tank 1965-1995, Osprey Publishing, 1995, p. 3.
52. Zahn, Brian R., The Future Combat System: Minimizing Risk While Maximizing Capability, USAWC Strategy Research Project, p. 13.
53. Simpkin, Richard E., Tank Warfare: An analysis of Soviet and NATO tank philosophy, Brassey’s, 1979, p. 192.
54. Joseph, Mallika, Arjun: India’s Main Battle Tank, Institute of Peace and Conflict Studies, June 2006, p. 2.
55. To be explained in greater detail in future Informatives.
56. http://63.99.108.76/forums/index.php?showtopic=18511
57. Held, Bruce J., Tomorrow’s Smart Tank Munitions, ARMOR Magazine, March 1995, p. 22.
58. http://www.globalsecurity.org/military/sys...ions/sadarm.htm

An excellent read, I enjoyed it. Definitely food for thought.

Isn't the real problem in the incoherency of calculating penetration scientifically, while taking claims of RHAe values for granted?

With all the discussion of M1 possibly achieving just 1200mm, in same weight as these NS tanks have, I believe it is.



Putting Wankbusters aside, how do we even know that NS RHA is the same as RL RHA? With the extreme popularity of titanium in NS, and everything making sense again with such assumption, it's quite likely to be that...

Does that mean T-80 or T-90 is then 12 times cheaper in maint than Abrams?

Well, it depends on the tank design IMO. The Nakíl didn't take the RHAe values for granted - they were calculated more or less scientifically. But, it should really weigh between 5 or 8 tonnes more! The problem is that both the glacis and the mantlet have a thickness of about 400mm. The mantlet's RHAe should have been less, admittedly, but the glacis RHAe could be right - it would just require much more weight.

Even discarding 3,000mm RHAe tanks, it's possible to reach 2,000mm RHAe.

What do you mean? The M1 can't achieve 1,200mm RHAe without gaining weight - it would add 1,500 to 2,500 kg of weight. But ERA is a very mass efficienct armor, it just suffers from limited technological utility (there probably won't be breakthroughs in ERA which will allow for dramatic increases in protection).

Because we assume that the chemical composition of NS steel is the same as modenr steel, given that we assume the same for every other material we use.

I don't get what you're trying to say. Titanium would have a value of RHAe. It just means how titanium compares to rolled homogenous steel in armor protection against different threats.

It could be. According to the same source, the T-55 is 3 times cheaper than the M60.

Within same weight package as M1A2, and with only increasing

The "More or less" part is troubling me, the only ways of estimating or measuring RHAe of armor to my knowledge are mass-efficiency factor for homogenous armors and live fire. The aforementioned factor is determined in live fire as well.

How much live fire has been conducted in developing and measuring NS armor schemes, 4/5 of which come right out the top of the head, and would almost surely be inferior to RL ones?
And how many of the other 1/5, coming from an article on the net, at least really claim the live fire proven results rather than "And then we add 10% for titanium, and 10% for uranium, and 10% for better ceramics, and 10% for NS, and 10% because I'm cool, and 10% because nobody will notice"?

I mean that in same total weight as NS tanks, on one of the best modern tanks, RL only makes possible 1,200mm, even that heavily ERA-based.

I'm starting to suspect the "RHA" in NS stands for armor plates made of titanium rather than steel.

Actually, it depends. There have been real-life chassis to have 2,000mm line of sight thickness that weight 48 tonnes! It's just a matter of working with a chassis by maximizing the depth of armor in certain areas. It's something I'm going to try to work with on the Lince, although I'm not an engineer (and probably won't be able to work something out - I'll have to compromise with lesser thickness).

The depth of armor protection on a turret is harder to attain, but attainable - such as the Falcon turret, or the Lince's turret (that you're aware of - don't want to reveal too much!). The use of an autoloader can drop a tank's weight by up to ten tonnes, so many of the tanks with high levels of protection that weigh around 80 tonnes really weight 90 tonnes or so, but save weight through autoloading (decreases armored volume of the turret).

That's why the Draftroom exists. ;) Thankfully, a lot of us have hundreds of papers which detail livefires on different materials so we can offer those RHAe figures. Very specific figures are hard to give because the majority of the users don't understand the math and don't really want to (admittedly, a lot of times that's me).

Mass efficiency can only be established through live fire, as well.

Using a thirty-year old armor scheme with minor improvements (depleted uranium) along the way. There are almost no new M1A2s, since most of them are modernized M1A1s, so armor is increased through thickness (if a new material is used it's used by increasing the thickness of the original armor). The only tanks I know of that can effectively take-off armor and put new advanced armor on are the Leclerc and Merkava tanks. The Israelis keep the RHAe values of the Merkava classified, but we know that the Merkava Mk. IV can survive a hit in the frontal 60º sector from a Kornet-E, which means over 1,500mm of RHAe versus HEAT.

Why? RHAe only means the equivalent efficiency of titanium as compared to RHA (rolled homogenous steel). Well, to be specific, old rolled homogenous steel. Even improved rolled homogenous steel (IRHA) has an RHAe rating!

I'm not sure I've seen any tanks on NS claiming more protection then the M1A2 with the same basic weight/dimension/crew/ammo stats. I've seen them a few tonnes heavier, with ERA, claiming 500-600mm more, which is roughly right. And I've seen heavier tanks, and tanks with radical new forms which effectivly cheat to get more armour for less "weight" (By decreasing some volume or rearanging it). But the only M1A2-characteristic tanks I've seen on NS that claim such excesses are all noobish attempts, or "PMT" as they claim.

Looks excellent, Mac! It will surely helps the noobs and even the veterans or aspiring-tank designers to decide what gun caliber and munitions they will use, and the advantages and disadvantages thereof.

Which reminds me. This is an important line you might want to underline, italic or something.

I know engines well enough to know how they work and to know how performance claims are done. I'll believe the 890 series when I see it, but I can assure you when they say the 880 series can do 1800hp, they mean 1800 on a bench with no load under ideal conditions. Put that in a tank, with a transmission and 60 tonnes to move, you just sucked 200hp away from that purely for all that crap. And then you need to reduce that another 100hp to give it leg room, to make sure you're not running it on the edge and don't have to rebuild it every other day. Or you can cheat and run a very different transmission system, like hydraulic, which changes the load patterns and makes it much more reliable at it's higher outputs.

Right from looking through the Army section, at designs specifically you haven't objected, I've found:
- 80t, 2800mm turret and glacis
- 80t, 2800mm KE, 3500 CE turret and glacis
- 75t, 3000/3300 turret, 2900/3200mm hull front, 1700/2000mm hull sides (better than the thickest part of any RL tank)

So does adding 12-15 tons to the tank more than double its armor protection?

On NS itself it gets even worse. I've seen a 72t tank claiming 2600/3000 turret and glacis, with a good load of armament of course, and making 100km/h.

Would go way better with specific paper giving protection per areal density figure, and then 3-view allowing to check the area of the various parts.

Links? I wanna see.

And if one of them is the older MCA-7B. There's a reason I've switched/brought about the G with that giant weight increase. That, and I've cheated with some serious layout and design changes over the Abrams that have alowed me weight savings, but I can discuss them with you in PM.

Protection doesn't so much have to do with weight, as volume. An M1A2 with 15 tonnes more armour won't double it's protection. But an M1A2 fitted with say, a Falcon turret, and on top of that 15 tonnes more armoure above it's original weight (Making near 30 tonnes of extra armour) probably will.

Which is why I like to say "A tank of simmilar weight/dimension/crew/ammo stats".

http://z4.invisionfree.com/NSDraftroom/ind...p?showtopic=963 (80t, 2800 front, though less outstanding than others)
http://z4.invisionfree.com/NSDraftroom/ind...p?showtopic=793 (75t, 2000mm side)
http://forums2.jolt.co.uk/showpost.php?p=1...2&postcount=204 (72t, racing grade)

And Falcon turret won't compromise any facet of its functionality?

The M8 I commented on, and why the armour was way too high. Another aspect of Nakil syndrome I presume.

To me anything Doom puts out falls into the realm of "PMT" as claimed, just because of the way he writes things and the technologies he takes. I agree the armour on that is high (Among other issues), but I've long since stopped caring what he does.

Having talked to TPF recently, he's abandoned that tank as silly as far as I know. Not every design posted ends up as "final".

Getting 2800mm of protection out of the glacias is surprisingly easier then you may think if you're using the Abrams as a base. And that, again, all comes down to a matter of layout. The Abrams goes for an incredibly thin glacias, but incredibly thick lower-front hull, to allow less mass on the front armour for simmilar protection, allowing greater mass to be put on the front of the turret, thus protecting the crew in a larger turret. The oposite can be done quite easily (The MCA-7 does it for instance).

Depends what you define as functionality. Will it make the crew a little more cramped? Yes, will it remove the ability to keep a 4th crewmember? Yes. Will it change the ammount of systems or ammunition the tank can carry? No. Nor will it change anything regarding what it can or can't do. It will of course place some restrictions, cramped turret for one, low vision height (Not nessecarily a bad thing), and limit the ready ammount of rounds (But not the total rounds carried, same situation as the LeClerc). Take for contrast the Merkava and Abrams turrets. The Merkava is extremely close in concept to the Falcon turret, narrow, with the bulk of the armour actually along the mantlet and forward sections of the side, providing thicker forward facing armour for lower weight. The Abrams on the other hand goes for the brute force approach for, well, a few reasons. One of which is stowage, the stowage ammounts of personal items of American tankers is enormus compared to those of other countries, and they prefer to keep a good chunk of that internally. The Israeli's strap it on the back of the turret, the Russians to the outside anywhere, and the Canadians have built extra bustle extensions just for that stuff. But the Abrams was designed to allow more stowage.

Edit: And just for the sake of it. The MCA-7B, on my records on my PC (On the laptop writing an essay right now) have the weight at just over 80,000kg. I can't remember the exact figure, but it's over 80, and below the G's current 86.8. I never bother to update anywhere else because, well, no one else uses the Nakil except about 8k I sold to TPF, and told him the weight was in the 80 tonne area, and someone who bought about 100 of the export model which was designed to be much lighter and he doesn't RP much anyway so I could care less. I'm shifting entirely to the G, that I'm happier with (And which mounts the 140mm gun less for different reasons then muzzle energy).
That all said, in consideration, some of your examples look like an extension of what was first posted regarding the MCA-7B, taking it's weights and protections. So, if people will dig things up like that to use as a base I should probably go edit in the correct weight figures sometime.

Seems to have missed the part that when guns get bigger and clumbsier, anti-tank guided missiles become more attractive. Especially as missile components, control, guidance and overall reliability improve.*

But such a postulation on NS would resault in something of a land based version of the AShM spammers vs Battleships debate. With hills and trees to muddle things further...

But then again, tank guns are also supposed to help blow big holes in fortifications.
With blowing up other tanks as a far second consideration...

*Somewhere while reading the second paragraph the 152 mm Shillegh and that Russian 125 mm equivilant SAM/ATGM thing came to mind.
------
As per wieght limits, it missed segmented or articulated multi-bogied tracks.
A rather odd way to get better mobility, most notable on certain arctic vehicles.

PROHT: You can also use ATGMs with various warheads (At which point they cease to be "AT" Guided Missiles) to provide demolitions capability, etc.

The biggest problem with relying on ATGWs is weapon speed. Even the quick ones take longer to reach a target than a APFSDS; and if you're shooting at a tank, you've probably illuminated that tank somehow (especially if the weapon is SACLOS) which means an LWR or RWR will be screaming at the tank crew who will, most likely, try to at least "kill you back" with their big 120/125/140mm Pain Stick.

Plus you can defeat a lot of ATGW with a good active protection system, or even the "passive" measures like SHTORA. Then there's ERA, which tends to be a lot more effective against those than a penetrating sabot. There are obviously workarounds to this (hypervelocity KEMs come to mind, as well as double and triple stage HEAT used against ERA, which is by no means a garuntee of penetration).

-LOBL IR, Passive, no illumination, downside is you have to get a steady lock and hope the seeker is good enough to stay locked once fired.

-blindfire with terminal laser homing (LOAL LH)
(May not lock on fast enough, enemy still sees rocket flash)

-LOAL IR homing
(quite a few issues with these, but it seems to work well with cluster bumb AT submunitions)

-TV wire guided (MCLOS?)
(The ever effective Swingfire? Or closer to the Walleye or Maverick air missiles)

Could make a KEM warhead as you suggested, with second stage rocket and penetrator included. (see also Gyrojet)
-Which would negate the capabilities of most countermeasures at expense of wieghing more than tank gun ammo of 155 mm, offset only by the fact that it would carry far less missiles (hopefully with better Kill Probobility and a stand off range) and doesn't require a massive gun to fire.

Would get rather odd when each 'tank' carried an pair of ATGMs, each the size of an IRBM. So tank guns and tank mounted ATGMs have their limits. Mostly because of the tank's own self imposed limits due to pre-existing infrastructure incapable of handling anything 'better'.

And that concludes the discussion/footnote of large ATGMs vs Large tank guns in the Large tank guns issues thread. (I hope)

See page one.

Does anyone remember that retarded scramjet tank shell fad? -_-

AN: I never noticed that, it was before I started paying a lot of attention to on-site / on-Jolt RP'ing. I suggest we move this conversation to the munitions subsection of the forum.

Yep.
It was a branch off from Pale Rider Arms gyrojet based munitions, right?

As for moving to munitions, sure. but what would we talk about?

This shows you can never know too much.

Just in case:

The issue with rocket, ramjet, scramjet assisted KEP is that they are only effective at low velocities. Otherwise the energy of such round is lower than it would be using just extra weight of tungsten.

At velocities of 1800-2000m/s and above, burning fuel becomes outright inefficient compared to using it as extra mass in penetration; extra hit of unburnt fuel mass is better than velocity gain from burning it.
At velocities of 1600-1900m/s, burning fuel per se wouldn't be a loss, but if we consider extra drag from the fuel (it takes 10 times more volume per kg than tungsten or DU), it's likely to result in small net loss at significant ranges and fuel not fully burning at shorter ranges; at best, negligible (within a couple percent) gains.
At 1400-1700m/s, rocket/etc assisted penetrator might be more effective per se, but it's doubtful if the small gain will outweigh potential accuracy loss and just needless complexity.
Of course, below 1500m/s, it's an improvement, but still stays questionable considering cost.

Data based on velocity-mass-penetration graphs and velocity gain for solid fuels.



I hope nobody is seriously considering a liquid fueled ramjet in APFSDS.

Assisted rounds are for extending the range of the KEP, not increasing penetration. If done right you increase penetration by virtue of angle of attack at range, but the whole point of an assisted round is to give that KEP muzzle velocity at such a distance, as if the tank were 1km closer when firing. Not as effecient as GLATGMs, but cheaper.

The point is that, for rounds with MV>1900m/s, a non-assisted round will have greater velocity at distance than assisted one, by the virtue of higher MV and lower drag.

At 1800<MV<1900, they can at the very best match their velocity at long range, but a non-assisted one will still be better at all ranges below and no worse beyond.


Basically, you can use an assisted round to retain say 1700m/s, but it's a waste of money for negligible return. You can't effectively use it to retain 2000m/s, or more precisely you'd get better results by adding some weight instead.

Of course it will have a higher muzzle energy, that's not the point of an assisted one. The point is so that at say 1000m, your round isn't traveling 1500m/s instead of the 1700m/s it left the gun at, so that at 1500-2000m it's traveling at it's ideal 1500m/s out that far. My point is that assisted rounds (Preferably rocket assisted, but ramjets if you wish) do absolutely nothing for penetrative power (In a relative sense, will explain below), it just extends your optimal range of penetration out. It's a long range round as an alternative to HEAT, or complimentary to it.

As for penetration. At longer ranges the angle of attack changes so instead of the LOS, or maybe 25 degrees off LOS, the round is comming in at 40 degrees, right into the top armour. It's not nessecarily increased penetration, but the likeyhood of penetration is because of the chances where you hit.

In the end all it does is complicate tank fights. Just add another range at which things open up. Long range assisted KEPs and some HEAT, medium with the HEAT, and then into the short range fight with the regular KEPs, where most of the tank on tank kills will happen anyway.

KEP have extremely long range without any assist as well. I don't have ballistic tables ATM, but it's something like 50m/s per km.

And as for range per se, I don't entirely believe that claim about 200km kill from Merkava (how did they confirm it?), but a program shows 180km ballistic range for IMI M338 at L55.



I will also note that newer penetrators are slower than older ones, as extra mass gives better penetration than extra speed.

Well I'm working on talking from tankers who specificly, although this is back before DU LRPs became popular, that they used HEAT warheads at ranges over 1000-1200m, because KEP rounds would simply not penetrate. Math can say one thing, but I tend to give real world experiance a bit more credance.

I think "before DU became popular" is the key factor. It's *far* denser and so more ballistic than anything used prior.

And have you talked to tankers who specifically said that assisted round do penetrate better at all ranges?
If not, it's no less theoretical than ballistic tables. Which are in fact experimental data.

There are no assisted tank rounds. There are base bleed rounds for arty, and some for tank-sized guns (100mm soviet base bleed shells) but that's it. There were experiments that all died with the end of the cold war though because there was no point. No Soviet/American supertank either side was worried sick about.

Like I said, it's just getting the round out there. The end result is that 90% of tank to tank kills are going to always happen within 1km, which is where assisted rounds are completely useless if not a problem anyway. Any tank of 40 round capacity is going to carry 4-6 assisted KEP rounds max anyway (I load 3), with most being HEAT, then conventional APFSDS, then Anti-Presonel, then GLATGM if they have them, with assisted being way in last place.

Although anyone I may go to war with in the future, please ignore the above and load all assisted KEPs.

That was my point.

It's also that at high velocities - >1800m/s - the assist is completely useless at any range.

However, M829A3 fires at 1550m/s. At these speeds long-range performance of assisted rounds might exceed conventional.

Just (2all) don't combine high velocity and assisted rounds.

The M829A3 impacts at ~1550m/s, not fires. There's a difference. It leaves the gun doing 200m/s more then that.

All kinds of factors suck energy from the round after it leaves the barrell. Especially like the factor of not being as well designed for aerodynamics as it could to prevent it from bouncing, breaking, or otherwise doing something stupid on impact while allowing greater mass.

Also, I bolded the most important part, which is basicly what we've both been saying here.

Missiles which don't need guns to be fired. The same missiles can be fired from a device similar to that on the Bradley, if you need a high-diameter missile - otherwise, you can use a 120mm missile. Large gun-launched missiles aren't as attractive as APFSDS, IMO, and so I don't see it as a justification. I mean, it's possible and there's nothing physically wrong with it, but it really doesn't have anything to do with what I'm trying to say either.

The MBT 70 was going to fire an improved version of the Shillelagh, but there are existing 120mm gun-launched missiles such as the LASAT. Various APFSDS designs are really gun-launched missiles, given that there are now a lot of APFSDS with integrated rocket motors (since the introduction of the idea with the Nakíl - at least, on a wide scale).

The Kornet-E penetrates roughly 1,500mm worth of RHAe according to online sources. The Merkava Mk.4 managed to successfully stop the penetrate of a Kornet-E along the 90º forward arc. I think normal HEAT missiles don't have a future with the application of advanced reactive armor, active protection systems and advanced passive armor arrays.

Well, the United States had an idea for the FMBT to mount around sixteen anti-tank missiles in the back of the hull of the multi-mission chassis (basis for the FCS) - the engine is forward-mounted. Can you imagine what people would do with that on NationStates?

How does this improve mobility, or width limits?

It allows for a larger percentage of terrain to be traversed (go versus no-go), but is a disadvantage in battlefield mobility.

I'll have to elaborate later, due to the fact that my sources on my PC at hime, but there have been successful test of rocket assisted KEPs at velocities higher than 1,800m/s with no decreases in penetration.

No, but the use of advanced materials and the reorientation of armor may. 2,800mm, admittedly, might be too high though. Nevertheless, it's not impossible. From what I've read in the Spanish Verdeja tank 40mm of steel on the glacis weighed roughly 7 tonnes - a bit more. The M1's glacis plate is composed of 30mm of chobham according to Michael Green's book, which means most of the weight is on the turret (around 300mm of chobham). I think the maximum thickness of the Leclerc is also 300mm - on the turret. Using an autoloader and smaller dimensions (it cramps the crew, however, and effects their ability to function over long periods of time) the Leclerc saves roughly 10 tonnes! The RHAe protection on the Leclerc is most likely fairly similar, depending on the source (if it's American it's probably less, and if it's French the armor is probably better and if it's neutral it's probably just under the RHAe levels of the M1A2).

I don't know how much the M1A2's turret plate can weigh, but it's probably around 20 tonnes. But, the Abram's armor is thirty years old.

That falls within Sumer's 'n00b' category.

Um, we're not engineers. :rolleyes:

The question isn't whether you can do it without decrease. It's whether you can obtain the same or better results through simpler means.

Glacis!=example. It's not normal armor, the only way glacis works is by being a nearly horizontal plate, so that any horizontal shot just scrapes it by, not hits.

So how much and what specifically has changed?

About 4% of Draftroom designers are. And it doesn't take one to draw a layout.

IMO, you can't. Rocket assisted KEPs can retain velocities over long-distances, so a penetrator can achieve ideal penetration at around 2,000m. Rocket assisted rounds can work in conjunction with ETC, or whatever else your gun works on. I don't see a disadvantage except cost.

What's your point?

... quite a bit.

It does take one to require a layout, and it does take one to make a layout accurate. I can make a layout of the Nakíl's armor and it doesn't make it anymore accurate than it already is.

So can non-assisted, according to their ballistic tables.

Unless there has just been a major breakthrough in the field of solid fuel rocket engines, and one unique to tank-fired ones, they simply don't even store enough energy to compensate the added drag at 2000m/s and end with net energy gain.
Might keep the speed, but at the expense of dropping penetrator mass.

Glacis=gtfo; it's not armor against normal hits, so there's no need to awe at how incredible the armor mass-efficiencies are just because someone has sloped his glacis another five degrees.

I mean just a top drawing showing where which armor section is, how high and how thick it is.

Allows for greater length to width ratios, or more track area in relation for a given tonnage.
(Albeit a modest improvement compared to the massive increase in length, plus it tends to only favor lightly armored designs)

As also noted by you, max-speed is severly limited by trying to synch up two or more powered chassis. But it does improve go vs no go, thus better mobility when reffering to 100+ ton gun tanks.

Width limits are a function of infrastructure, length per hull is dictated by width, tonnage dictated by ground pressure (tracks) and the ground itself.

But most of that goes away (except turret ring limits, which can be quitely forgotten if you use a fixed gun mount) when you use seprate hulls for each component.

There is a reason why we most likely won't ever see [tanks] carrying anything bigger than 203 mm, even on NS. Which would be a super-heavy tank gun. The aformentioned and postulated 140 to 203 mm tank gun would of course still have issues outlined in the OP and such (rather than my offshot of ATGMs and SHTGs).

Rocket assist = the new APCBC in an AP capped world, or is it the exact opposite of APCR?
(Performance wise, not in construction)

For some reason I don't trust the idea of trying to guide a LRP.
(For one, TiF is pretty hairline small, meaning LOBL is a must, and even that might not be good enough, as then it becomes a race between getting a lock vs simply aiming the darn thing right)

For the record, I've been working on a set of such diagrams, showing armour coverage (Real), internal structure, and that. But my drawing skills are not what I want them to be for me to like what ends up drawn.

A non-assisted APFSDS can't attain 2,000m/s over 2km unless the velocity it was fired at was over roughly 2,200m/s - which is possible. On the other hand, there's a large chance that you're going to engage at 500m, at which range the penetrator will lose penetration efficiency at such high velocities. With a rocket-assisted projectile you can fire the projectile at the velocity you want and retain that velocity over a long distance - rocket weight doesn't necessarilly need to be high and it doesn't necessarilly need to be bulky.

It's an added disadvantage, but in a desert environment where engagement ranges can be higher than 2km then the advantages are worth the added weight. For the Lince, on the other hand, there isn't that large of an advantage because engagement ranges will most likely be at around 500m.

Real-life ballistic data doesn't agree with you. I'll have to get the information from my house tonight, but there are other examples that I don't have any specific papers on. Apparently, there are existing APFSDS rounds for the A-10's 30mm which have the same penetratio at 1,600m that they do at 1,000m. The important information I'll have to get is the integration of the RAMjet with the round to decrease added mass.

The loss in penetrator mass is not that high. You can regain penetrator mass by decreasing muzzle velocity and having the engine reach that velocity for you. But, you effectively make the engine larger or you decrease its effective range. Nevertheless, a rocket assisted AFPSDS can reach ranges of some 6 to 8 kilometers which is unecessary for an APFSDS, so a loss in range isn't necessarilly that bad.

A guided round, in any case, will require some sort of extra propulsion or vectoring.

Yea, but you're ignoring the high levels of protection it achieves. You can effectively decrease the thickness of the glacis and add it to the turret - which is the point. You are achieving high levels of protection elsewhere by sacrificing thickness elsewhere, yet still retaining almost equal protection in both cases.

In any case, you effective missed my point (like you tend to do) and completely went off on a tangent (which I, at first, didn't catch). My example only mentioned the fact that the majority of the armored weight is in the turret - so I was trying to give an idea of what the armor on the turret could effectively weigh. You somehow managed to completely miss what I say and go off on a completely different topic.

Why? You can describe it's location with rough wording and most good write-ups include actual thickness.

Tilting the glacis beyond a certain point = loss of volume per area of armor = you still phail

Plus now your tank has this huge 'nose' to impale itself into the ground with and trigger AT mines with fatal resaults.